Research Roundup: A light in the darkness of depression

Rebekah Hayes

Clare Dolman shares exciting new research on Bright Light Therapy for bipolar.

Researchers in the US have found a way to significantly reduce the depression of a group of people with bipolar with a treatment that has no side effects and is very cheap to administer.

Exposure to bright white light has been shown to reduce symptoms of people with Seasonal Affective Disorder (SAD) before, but patients with bipolar given similar treatment can experience side effects such as mania or mixed mood symptoms. The key was to carry out the treatment at the right time of day.

Project lead Dr Dorothy Sit of Northwestern University said:

"As clinicians, we need to find treatments that avoid these side effects and allow for a nice, stable response. Treatment with bright light at midday can provide this”.

The study, which was published this month in the American Journal of Psychiatry, included 46 participants who had bipolar and at least moderate depression, and who were on a mood stabiliser. Patients were randomly assigned to either a 7,000 lux bright white light or a 50 lux placebo light. The light therapy patients were instructed to place the light box about one foot from their face for 15-minute sessions to start. Every week, they increased their exposure to the light therapy by 15-minute increments until they reached a dose of 60 minutes per day or experienced a significant change in their mood.

"By starting at a lower dose and slowly marching that dose up over time, we were able to adjust for tolerability and make the treatment suitable for most patients," Sit said. They also observed a noticeable effect of bright light therapy by four weeks, which is similar to other studies that test light therapy for non-seasonal depression and depression during pregnancy.

Compared to dim placebo light, study participants assigned to bright white light between noon and 2:30pm for six weeks experienced a significantly higher remission rate (minimal depression and return to normal functioning). More than 68% of patients who received midday bright light achieved a normal level of mood, compared to 22.2% of patients who received the placebo light.

The group receiving bright light therapy also had a much lower average depression score of 9.2 compared to 14.9 for the placebo group and significantly higher functioning, meaning they could go back to work or complete tasks around the house they hadn't been able to finish prior to treatment.

Bipolar UK trustee Professor Allan Young commented: “Bipolar disorder has long been thought to be linked to disruptions of daily rhythms. Bright light seems to be an efficacious (and likely safe) way to treat bipolar depression and it is to be hoped that sufferers from bipolar depression might benefit from this approach”.

Dr Sit and her research group are planning to conduct new studies to investigate the mechanism of response to light in bipolar disorder.

"Effective treatments for bipolar depression are very limited," said Dr. Sit. "This gives us a new treatment option for bipolar patients that we know gets us a robust response within four to six weeks."